Connector



April 21, 1964 J. D. ROUNTREE 3,130,269

CONNECTOR Filed March 15, 1961 INVENTOE: JOSEPH D. ROUNTEEE,

HTToQNEWs United States Patent O 3,139,26? Qfifat EETOR Eoseph I). Reuntree, 1%6 St. Qiair Ave, East t. Louis, Ill. Filed Mar. 13, 1961, Ser. No. 95,394 3 11121211". (*Cl. 1791) This invention relates to an electrical connector of the plug and socket type and especially to a connector having an interlock for normally resisting unplugging of the connector, but readily permitting separation of the plug from the connector when they are pivoted relative to one another.

The socket of this connector is formed of a resilient material, such as rubber, with recesses or cavities for receiving the contact prongs of the plug. These contact prongs have enlarged ends or heads of greater size than the diameter of the cavities so that, when inserted into the cavities, Le heads wedge the side walls of the cavities outwardly. The parts of the contact prongs adjacent the enlarged heads are of about the same diameter as the cavities. Therefore, after the heads of the prongs have been pushed past the part of the cavities adjacent their open ends, these cavity parts spring back to the normal positions to releasably lock the prong heads within the cavities. The composition of the socket material and the shapes of the prongs are such that a relatively great force is required to unplug the connector by pulling the plug and the socket apart; but the connector will readily unplug when the plug is pivoted relative to the socket.

A principal object of the invention, therefore, is to provide an electrical connector having a plug and socket that will remain locked together against strong pulling forces but that can be disconnected by the application of relatively low magnitudes of pivoting forces.

Another object of the invention is to provide a connector including a plug and socket wherein the plug can be disconnected from the socket by pivoting the plug relative to the socket and wherein such a low pivoting force is required that the force can be applied to the cord of the plug without damage to the wiring of the connector.

Another object of the invention is to provide a connector that can be used in a drive-in theatre sound system or the like, including a socket mounted on an automobile and a plug connected to a master sound circuit, wherein the connections of the plug to the socket may be broken by simply driving the automobile away from the plug.

Other objects and advantages will appear.

In the drawings:

FIGURE 1 is a typical side view of both the socket, part of which is in section, and the plug, also partly in section, of this connector;

FIGURE 2 is another typical side View of the connector with the plug connected to the socket; part of the socket is in section;

FIGURE 3 is a typical side view of the connector showing how the plug is removed from the socket. Again, part of the socket is in section; and

FIGURE 4 is a schematic plan view, partly in section and partly broken away, of the connector as used for a drive-in theatre sound system.

This connector comprises a socket 1t) and a plug 11. The socket 113 has a socket body 12 that is molded of rubber or other resilient insulator material.

The body has a front face 13. Extending within the body 12 from its front face 13 are a pair of cavities 14 and 15. The cavities 14 and 15, while being of greater depth than width, are shallow. These cavities are illustrated as being generally cylindrical in shape. Other shapes are possible, and even desirable under certain circumstances, as will be explained.

A two conductor cord 16, about which the body 12 is molded, extends into the body. One conductor 17 is soldered or otherwise connected to a conductive plate 18 (of copper or the like); the other conductor 19 is soldered to a similar conductive plate 20. One plate 18 is pressed against the rear wall of the cavity 14; the other plate 25 is pressed against the rear wall of the cavity 15. Both plates are sufiiciently thin for flexibility and will conform to the shapes of the cavity walls when the cavities are deformed.

The plug 11 has a plug body 21 of rubber or other insulator material with a front face 22. The plug body 21 is molded about a two conductor cord 23, the individual conductors 24 and 25 of which are separated within the plug body 21.

The plug 11 has two contact prongs 26 and 27 corresponding to the conductors 24 and 25 and spaced apart by the same distance as the spacing between the cavities 14 and 15. The contact prongs have portions 23 and 29 imbedded within the plug body 21. The conductors 24 and 25 are soldered or otherwise connected to these imbedded portions of the contact prongs 26 and 27.

The shapes of the prongs 24 and 25 have special significance to this invention. Each of the prongs has a shaft portion 36 that extends from the face of the plug body 21. The diameter of each shaft portion 30 is the same as or greater than the diameter of a cavity 14 in the socket body 12. The shaft portions 30 are short; adjacent to them, the contact prongs 26 and 27 are formed with enlarged heads 31 of greater diameter than that of the cavities 14. The heads 31 are preferably spherical in shape, although other shapes are possible so long as the heads 31 extend laterally beyond the shaft portions 31?. The length of the contact prongs 26 and 27, measured from the face 22 of the plug body to the extreme end of the heads 31, is the same as or slightly greater than the depth of the cavities 14- and 15.

It has been mentioned that the shapes of the cavities 14 and 15 may be cylindrical. If the cavities are of such shape, the prongs will displace that portion of the side walls of the cavities in contact with the heads 26 and 27 of the prongs. It is to be understood, however, that the cavities 14 and 15 may have shapes corresponding to the shapes of the contact prongs 26 and 27. Then, when the prongs are inserted into the cavities, they will displace the portion of the cavities adjacent their open ends, but these portions will return to their undistorted shapes when the prongs are fully inserted. Thereafter, the previously displaced portions of the cavities will releasably lock the prongs against removal. The prongs when fully inserted, however, do not displace much (if any) or" the side wall of the cavity because of the larger diameter of the closed end of the cavities. This configuration of the cavities produces a greater locking action and requires a greater force for unplugging, compared to the cavities of cylindrical shape.

The insertion of the contact prongs 26 and 27, all the way into the cavities 14 and 15 so that the heads 31 contact the plates 18 and 29, establishes an electrical connection between the conductors of the cord 16 and the conductors of the cord 23. This condition of the connector is illustrated in FIGURE 2. Even then, however, there may be a space between the face 13 of the socket body l2 and the face 22 of the plug body 21 produced by the difference between the lengths of the contact prongs and the depth of the cavities.

Operation The socket 10 and the plug 11 are especially designed to remain locked together under normal circumstances, but, when desired, to be readily and virtually eifortlessly unplugged. The locking occurs because, as illustrated in FIGURE 2, when the prongs are fully (or almost fully) extended within the cavities, the heads 31 of the prongs displace the walls of the smaller cavities at the areas of contact. While this localized displacement or stretching occurs, however, the shaft portions 39 of the prongs, because of their smaller diameters, cause little or no stretching of the portions of the cavities they contact. Hence, the resilient socket body establishes a yieldable annular shoulder 32 that surrounds each shaft portion 34) of the prongs. Since the annular shoulders 32 are smaller in diameter than the diameter of the prong heads 31, these shoulders rele-asably lock the heads of the contact prongs within the cavities.

While it is possible to unplug the connector by pulling the plug 11 straight away from'the socket 10, the stiffness of the rubber or other material forming the socket body 12 is a determining factor in the amount of force required to pull both prongs from thesockets simultaneously. The other factors that control the required magni tude of pulling force are the sizes of the prong heads 31' relative to the cavities 14 and 15, and the over-all length of the contact prongs 26 and 27. In the preferred con struction of the connector, these factors are combined to produce an interlock between the plug and socket that requires a strong force to unplug it.

Whether the holding force of the connector is strong or relatively weaker, the connector can be unplugged by the exertion of a much smaller force than that required to simultaneously release both contact prongs from the cavities. This easier unplugging of the connector is ac complished by pivoting the plug 11 about an edge of the face 32 opposite one of the contact prongs 26 or 27, thereby releasing only one of the contact prongs. F or example, FIGURE 3 shows the contact prong 26 being removed from the cavity !14- as the plug 11 is pivoted about an edge of the face 22. The slight space between the face '13 of the socket body and the face 32 of the plug body allows an initial pivoting of the plug 11 about the head 31 of the contact prong 27 until the edge of the plug body face 22 contacts the socket body face. At that time, the fulcrum, about which the plug pivots, shifts from the contact prong head to the edge of the plug body face.

The initial pivoting of the plug 11 about the head 31 of the contact prong 27 allows the shaft portion St} of the other contact prong 26 to withdraw from the cavity 14, with the head 31 of the contact prong 26 moving to the open end of the cavity 1d, all without any withdrawal of the contact prcng'27. As the head $1 of the contact prong 26 moves toward the open end of the cavity 14, it spreads that end of the cavity, while the seat of the cavity vacated by the prong head springs back to its normal shape. This seat or rearward part of the cavity :14 then exerts a pressure force against the head of the contact prong 26, tending to aid in the expulsion of the prong from the cavity. Thereafter, final removal of the contact prong from the cavity 14 as the plug 11%1 is pivoted about the edge of its body face 22 requires little additional pulling force.

Another effect of the space between the socket face l3 and the plug face 22, allowing the initial pivoting of the plug 1 1 to take place about the head 31 of the contact prong 27, is that the path of initial withdrawal of the head 31 of the contact prong Z6 is approximately parallel to the axis of the'cavity, a condition that is maintained while the contact head moves to the open end of the cavity 14, or until the pivot fulcrum shifts to the edge of the plug body face 22. This path of movement of the contact prong 26 is conditioned upon the overall length of the contact prongs and upon the shortness of the shaft portion relative to the head 31.

This space between the faces 13 and 22 is of significance when the edge of the plug body face 22 does not extend far beyond the prongs in a lateral distance. With such a design of the plug body, if the initial pivoting occurred about the edge of the plug face 22, the head of the prong would dig into the side wall of the cavity with consequent resistance to unplugging. If the plug is wider, however, with the edges of the face 22 extending sufiiciently beyond the prongs in a lateral direction (preferably at least as far as the length of the prongs), the space between the plug and socket faces may be eliminated.

Once the prong :26 is freed of the cavity 14, continued pivoting of the plug 11 about the edge of its face 22 withdraws the other contact prong 27 from the cavity 15-.

lthough two contact prongs and cavities are illustrated and described, there may be other members. The connector will always runplug easier when the plug is pivoted than when all the cont-act prongs are simultaneously pulled from the socketcavities.

While it is easier to release the prongs singly by pivoting the plug head about its edge furthest from the prong to be released first, the force required to unplug the connector by pivoting the plug about any portion of the edge of the plug face is considerably less than the force re-: quired to pull the plug straight away from the socket.

in other words, the design of the prongs allows the application of leverage to unplug the connector when the plug is pivoted about any portion of the edge of its face.

This connector has utility in any electrical circuit when a releasable connection is to be made. It improves upon conventional connectors which require grasping of the plug body for safe unplugging without undue stresses upon the plug wires. The force required to unplug this connector when its plug is pivoted in the proper direction is so small that pulling upon the plug cord 23 will not break the connection of the conductors 24 and 25 with the contact prongs 26 and 2 7.

A special use for the connector is to connect the speaker of an automobile radio to a pair of conductors that are transmitting movie accompanying sound at a drive-in theatre. Such an arrangement is diagrammatically illustrated in the plan view of FIGURE 4 wherein the socket It? is mounted in a hole through a side panel 35 of an utomobile. The socket should be oriented with the cavities 14 and 15 generally parallel to the ground but this orientation is not strictly required for the successful operation of the connector. The conductors 17 and 19 are connected to the terminals of an automobile speaker as. The cord 23- of the plug 1 1 is wired to a master sound circuit (not shown) by way of a weather resistant post 37 or other standard. A number of such posts or standards 37 are provided according to the automobile capacity of the drive-in theatre.

With a drive-in theatre sound system of this type, each customer merely parks his car and plugs the plug 11 into the socket 1t} mounted to 1 is car. There are, therefore, no boxes and wires to be placed within the car, nor open windows required to accommodate such boxes and wires. And when the customer is ready to leave the theatre, he does not need to get out of the car and unplug the connector, but can merely drive away from the plug 11. As the customers car pulls away, the wire 23 connected to the post 37 will retain the plug 11 causing it to pivot away and unplug from the socket 10 in the manner al ready described.

This invention is intended to include not only the plug and socket described in detail, but also various adapters, multifaced sockets, and the like, as well as any other devices having a socket for receiving the prongs of a plug or having a plug with prongs for insertion into a socket.

Various changes and modifications may be made within the process of this invention as will be readily apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

What is claimed is:

l. A connector comprising a plug and a socket, the plug having two prongs and the socket having two cavities corresponding in relative position to the relative position of the prongs, each prong having a short shaft portion and a round head on the end of the short shaft, the diameter of the short shaft being substantially less than the diameter of the head, the cavities being of less depth than the length of a prong, the mouth of each cavity being of substantially the same diameter as the diameter of the short shafts, the socket being of yieldable resilient insulator material, an electrical contact element disposed entirely within each cavity and spaced from the mouth thereof, whereby contact with a prong is made only when the prong is substantially fully inserted in the socket, and whereby the electrical contact does not interfere with the yieldability in all directions of the mouth of the cavity, the plug having edges spaced a distance from the prongs at least substantially as far as the length of the prongs.

2. The combination of claim 1 wherein each cavity is of substantially uniform diameter over its entire depth so that the head of a prong displaces the walls of the cavity when inserted therein and the resilience of the cavity Wall helps expel the prong when the plug is pivoted relative to the socket.

3. The connector of claim 1 wherein the socket is mounted to the panel of a vehicle with the cavities substantially parallel to the ground beneath the vehicle and is wired to a radio speaker within the vehicle and the plug is wired to a sound system independent of the vehicle.

References Cited in the file of this patent UNITED STATES PATENTS 2,201,045 Lundstrorn May 14, 1940 2,619,544 Satterfield Nov. 25, 1952 2,765,365 Grosh et a1. Oct. 2, 1956 

1. A CONNECTOR COMPRISING A PLUG AND A SOCKET, THE PLUG HAVING TWO PRONGS AND THE SOCKET HAVING TWO CAVITIES CORRESPONDING IN RELATIVE POSITION TO THE RELATIVE POSITION OF THE PRONGS, EACH PRONG HAVING A SHORT SHAFT PORTION AND A ROUND HEAD ON THE END OF THE SHORT SHAFT, THE DIAMETER OF THE SHORT SHAFT BEING SUBSTANTIALLY LESS THAN THE DIAMETER OF THE HEAD, THE CAVITIES BEING OF LESS DEPTH THAN THE LENGTH OF A PRONG, THE MOUTH OF EACH CAVITY BEING OF SUBSTANTIALLY THE SAME DIAMETER AS THE DIAMETER OF THE SHORT SHAFTS, THE SOCKET BEING OF YIELDABLE RESILIENT INSULATOR MATERIAL, AN ELECTRICAL CONTACT ELEMENT DISPOSED ENTIRELY WITHIN EACH CAVITY AND SPACED FROM THE MOUTH THEREOF, WHEREBY CONTACT WITH A PRONG IS MADE ONLY WHEN THE PRONG IS SUBSTANTIALLY FULLY INSERTED IN THE SOCKET, AND WHEREBY THE ELECTRICAL CONTACT DOES NOT INTERFERE WITH THE YIELDABILITY IN ALL DIRECTIONS OF THE MOUTH OF THE CAVITY, THE PLUG HAVING EDGES SPACED A DISTANCE FROM THE PRONGS AT LEAST SUBSTANTIALLY AS FAR AS THE LENGTH OF THE PRONGS. 